1. Field of the Invention
The present invention relates to a card-shaped memory device such as a memory card, which incorporates multiple IC chips.
2. Description of the Related Art
A small memory card serving as a data storage medium for, e.g., a digital camera or cell phone has been developed. The memory card can exchange data with a host device, such as the digital camera or cell phone, while it is inserted in the host device. The memory card comprises a circuit substrate on which, e.g., a nonvolatile semiconductor memory chip and a memory controller chip are mounted, and a package accommodating the circuit substrate. Memory cards having increasingly smaller size and greater memory capacity have been produced in accordance with which, techniques have been developed by which the memory chips are incorporated into the memory card and stacked together (as disclosed in, e.g., Jpn. Pat. Appln. KOKAI Publications Nos. 2001-160125, 2000-123141 and 11-204720).
In recent years, the functions of memory cards have diversified. As a result, as well as a data storage function, a memory card is required to have a so-called IC card function which enables it to double as a financial card such as a credit card, cash card or prepaid card, and an ID card such as a driving license or passport.
It is necessary to reliably prevent a chip having such an IC card function from being broken by stress when the memory card is manufactured or used, since it stores vital data such as accounting information.
Furthermore, since the chips incorporated in the memory card have different functions, it is required that each chip be easily manufactured and easily testable during manufacture.